The present invention relates to a microwave filter equipped with a plurality of cavity resonators which are coupled with one another via coupling irises disposed in their side walls and extending parallel to the direction of wave propagation.
Such a microwave filter is disclosed in U.S. Pat. No. 3,969,692. To attain the highest possible filter quality (Q), all mutually coupled cylindrical cavity resonators of this microwave filter are operated in the TE-011 mode. In order to realize an elliptical filter characteristic, the cavity resonators of the prior art microwave filter are combined in a rather complicated arrangement in that, in addition to coupling together the cavity resonators which are arranged in succession in the direction of energy flow, positive or negative cross couplings are produced between other cavity resonators.